1. Field of the Invention
The present invention relates to a decoding device and method for receiving bitstreams including coded, multiplexed video, audio, and so on, and extracting coded data from each bitstream to decode the coded data.
2. Description of the Prior Art
When a prior art decoding device decodes an input bitstream, including coded, multiplexed data, such as video, audio, and so on, the bitstream forming a hierarchy comprised of packs, each of which is high-level information, and packets, each of which is low-level information, it detects a pack header from each pack and then detects a packet header based on pack header information included in the pack header detected. At that time, the prior art decoding device can detect errors in the pack header information, such as a stuffing length or a pack header length, within the pack header, and then detect the packet header only when there is no error in the pack header information. The prior art decoding device then detects packet header information from the packet header, and also tries to detect errors in the packet header information, such as a stuffing length and a packet header length, within the packet header. Only when there is no error in the packet header information, the prior art decoding device separates a coded data region from each packet included in the bitstream, including coded, multiplexed data, such as video, audio and so on, and then extracts coded data from the coded data region.
In addition, when the coded data region separated includes a private data other than the coded data, which is information associated with the coded data, the prior art decoding device tries to detect errors in the private data and then decodes the coded data only when there in no error in the private data.
In an audio information coding system which conforms to a DVD-Video standard, such as Dolby digital, linear PCM, or MPEG audio, the private data other than the coded data, which is information associated with coded data, is a coded data placed and multiplexed as a private stream packet in the coded data region. For example, the private data can be either audio frame information indicating the number of audio frames within each packet or audio data information indicating the number of audio channels.
Japanese Patent Application Publication No. 8-251146 discloses another prior art decoding device that can send an error detection result including a resend requirement, as a response packet, to the sender when it detects an error in a data packet included in another input bitstream, and then replace the data having an error with a data that is resent thereto.
A problem with prior art decoding devices constructed as above is that if the pack header information within each pack header includes an error, the packet header cannot be detected and an error process is carried out even though the packet data hierarchically arranged in each pack does not include any errors and the coded data is correct. Further, an error detection in the packet header information triggers an error process and hence prevents the coded data from being decoded even though the pack header information does not include any errors and the coded data is correct. In addition, an error detection in information associated with the coded data, other than the coded data, which is placed in the coded data region of each packet, prevents the coded data from being decoded even though any one of the coded data, pack header information, and packet header information does not include any errors.